In prior commercial coin operated lock units of the type described for example in U.S. Pat. Nos. 3,228,506 and 3,599,770, a coin gauging lever is supported on a side wall of the coin chute for pivotal movements between coin gauging and release positions. When in gauging position, the lever cooperates with a front edge of a coin chute or other suitably defined gauging surface to gauge the size of coins deposited in the coin chute and to temporarily support a properly sized coin in a coin sensing position or station, wherein it can be sensed by a coin feeler finger, which thereupon frees a patron key controlled lock for rotation from its unlocked into its locked position. Rotation of the patron lock into its locked position or subsequent removal of the patron key from the patron lock frees the coin gauging lever for pivotal movement into a release position permitting the previously sensed coin to fall by gravity for discharge from the lock unit; the lever thereafter being forced to return to its gauging position as an incident to the return of the patron lock to its unlocked position or reinsertion of the patron key.
A decided drawback of these prior lock units is that they are limited in use to operation by a single coin.
Various attempts described for instance in U.S. Pat. Nos. 3,938,640; 4,131,191; 4,153,150 and 4,423,805 have been made to adapt or retrofit previously installed lock units of the type described in U.S. Pat. Nos. 3,338,506 and 3,599,770 for operation of two or more coins, but such attempts have met with only limited success.